(1.) Field of the Invention
The present invention relates to a magnetic disk cartridge which magnetically records and holds information.
(2.) Description of the Related Art
A conventional magnetic disk cartridge is designed as follows.
In general, nonwoven fabric liners are adhered respectively to the inner surfaces of a separate type plastic cases, with a rotatable magnetic disk disposed therebetween in such a way that the surfaces of each liner may contact the both sides of the magnetic disk. The liners each serve as cleaning sheet and a prevention against abrasion of the magnetic disk surfaces.
The liner may be designed as disclosed in Japanese Unexamined Utility Model Publication No. Sho 63-52184 in such a manner as to have three long protrusions formed thereon protruding on the magnetic disk side and extending radially.
With the use of such a liner, the long protrusions strongly contact with the magnetic disk to clean the disk surface while the other portion of the liner touches the disk very lightly, resulting in a small frictional resistance. The liners will not interfere with the fast rotation of the magnetic disk.
Since the long protrusions on each liner of the conventional magnetic disk cartridge extend radially, however, when the magnetic disk rotates, the surface of the disk always contacts the radial long protrusions at almost the same angle. The contacting pattern does not therefore change, making the liners exert an insufficient effect to clean the magnetic disk.
In addition, to form the long protrusions radially on the liner, it is necessary to cut a rolled liner sheet in a disk shape before forming radial long protrusions on the cut liner by pressing, or after forming radial long protrusions on the liner sheet. In this method, centering of the disk shape liner is indispensable and therefore the productivity of magnetic disk cartridge will be remarkably reduced.